Could new blood test prevent ‘Alzheimer’s of the eye’?

A new blood test has been developed that could save the elderly from a condition known as the ‘Alzheimer’s of the eye.’ By detecting macular degeneration before the symptoms begin, the sight of many older people could be maintained when it would otherwise be lost.

The condition affects five million people across the planet, but many do not realise they have age-related macular degeneration (AMD) until their vision starts to disappear. Dark spots appearing or words vanishing as they are read on a piece of paper are common symptoms, but these start once the damage is already done.

AMD is the leading cause of blindness in those over 50, but ophthalmologists believe the new test could change that. Early diagnosis means treatment can be administered at the vital stage when the injections can still stop it in its tracks.

While still in the wet form of AMD, injections can block the overgrowth of leaky blood vessels in the eye. Saving a person’s eyesight can have a huge impact on the rest of their lives – from their quality of life to maintaining their independence for as long as possible.

Dr Joan Miller, co-author of the study, chief of ophthalmology at Massachusetts General Hospital, and a professor at Harvard Medical School, said: “Because the signs and symptoms of early stage AMD are very subtle, with visual symptoms only becoming apparent at more advanced stages of the disease, identification of biomarkers in human blood plasma may allow us to better understand the early to intermediate stages of AMD so we may intervene sooner, and ultimately provide better care.”

The blood test is based on 87 molecules, the majority of which are lipids, which can build up as yellow deposits in the retina. Those with higher levels were found to be at greater risk of developing AMD.

Interestingly, one of these lipids is also associated with Alzheimer’s, another form of degenerative disease. Identifying it in a patient could therefore lead to treatment for both conditions and mean a completely different outlook.

Co-author Dr Deeba Husain, a retina specialist at Masachusetts Eye and Ear Infirmary, said: “We believe this work will help launch the era of personalised medicine in treatment of AMD.

“Our work gives us a novel biomarker for early diagnosis, and it gives us clues to differentiate the progressors from non-progressors. This research also gives us insight into the important role of lipids in AMD, which will provide novel targets for treatment in the early stage of disease, thus preserving vision in AMD.”

In order to carry out the research, scientists took blood samples from a 90 people with varying degrees of AMD. These included early, intermediate and late-stage cases of the disease. They were then compared to 30 individuals who are free from the condition.
It is likely the blood tests will be rolled out to those who are at greater risk of developing AMD. These include people who have been exposed to excessive sunlight throughout their lives, individuals with high blood pressure and those who drink or smoke heavily or are obese.